It is known to equip an indoor unit of an air conditioner with an opening and closing panel that covers a suction port, which is provided in a casing. This opening and closing panel covers the suction port when the operation of the indoor unit of the air conditioner is stopped, thereby making it possible to conceal the suction port from external view and thereby improve the design qualities of the indoor unit. In addition, the movement of the opening and closing panel so that the suction port opens ensures the intake of air when operating the indoor unit of the air conditioner (refer to Japanese Published Unexamined Patent Application No. H7-98129, FIG. 1). It is thereby possible to simultaneously achieve good design qualities and ventilation performance.